Reflexes of the Orbital Region

Question 1

what are the 3 divisions of the trigeminal nerve (CNV)

Answer 1

V1- opthalmic
V2- maxillary
V2- mandibular

Question 2

what does the ophthalmic nerve innervated (V1) (sensory)

Answer 2

upper eyelid
cornea
conjunctiva
skin of the root/bridge/tip of the nose

Question 3

what does the maxillary nerve innervate (CNV2) (sensory)

Answer 3

skin of the lower eyelid
skin over maxilla
skin over the ala of the nose
skin/mucosa of upper lip

Question 4

what does the mandibular nerve (cNV3) innervate (sensory)

Answer 4

skin over mandible and temporomandibular joint (apart from angle of the mandible)

Question 5

what foramen does the ophthalmic nerve travel through

Answer 5

supraorbital fossa

Question 6

what foramen does the maxillary nerve travel through

Answer 6

infraorbital fossa

Question 7

What is the sensory component of the ‘blink reflex’

Answer 7

CNV1 - The ophthalmic nerve

Question 8

what is the pathway of the action potential in the blink reflex

Answer 8

CNV1– trigeminal ganglion – along trigeminal nerve – to pons – to motor nerve (CNVII - facial)

Question 9

what is the motor component of the blink reflex and what does it do

Answer 9

CNVII - facial nerve

causes the closure of the eyelid via the orbicularis oculi

Question 10

at what level do sympathetic neurons leave the spinal cord

Answer 10

T1-L2

therefore thoracolumbar output as the sympathetic neurons follow T1-L2 nerves to get to the sympathetic chain

Question 11

where do sympathetic axons go after the sympathetic chain

Answer 11

run out in all spinal nerves to the splanchnic nerves which take them to organs

Question 12

what phrase describes the sympathetic nervous system

Answer 12

‘fight or flight’ segment of the autonomic nervous system

Question 13

how do post synaptic sympathetic fibres make it from T1 up to the eye

Answer 13

synapse at the superior cervical sympathetic ganglion

travel up the internal and external carotids

pass onto the surface of the carotids

carried to organs of the head on the surface of the branches from the carotid artery

ophthalmic artery carries sympathetic axons into the orbit

Question 14

where do parasympathetic axons leave the spinal cord

Answer 14

Via cranial nerves III. VII, IX and X as well as sacral spinal nerves

therefore known as cranialsacral outflow

Question 15

what is phrase that describes the parasympathetic nervous system

Answer 15

‘rest and digest’ segment of the autonomic nervous system

Question 16

what do the parasympathetic ganglia in the head supply

Answer 16

the eye
the lacrimal gland
the salivary glands

Question 17

where does the occulomotor nerve connect with the CNS

Answer 17

between the midline and the pons

Question 18

where does the oculomotor nerve exit the skull

Answer 18

superior orbital fissure

Question 19

what does the oculomotor nerve provide somatic motor innervation to

Answer 19

Superior rectus 
medial rectus 
inferior rectus 
inferior oblique 
elevator palpebrae

Question 20

what do the ciliary nerves innervate

Answer 20

supply autonomic axons to control the diameter of the iris and refractive shape of the lens

Question 21

what are the long ciliary nerves

Answer 21

sympathetic
somatic sensory

first part of blink reflex

Question 22

what are the short ciliary nerves

Answer 22

sympathetic and parasympathetic

Question 23

what are the autonomic reflexes of the eye

Answer 23

• wide eye - maximal eyelid elevation
• pupillary dilation/constriction
• focussing lens for far and near vision
• Lacrimation reflex tear production
• vestibulo-ocular reflex (stabilises gaze during head movement)
• oculocardiac reflex (bradycardia in response to tension on the eye)

Question 24

what are the functions of the sympathetic nervous system on the eye

Answer 24

• opening eyes wider
• gets more light into eyes (dilation)
• focuses on far objects
• emotional lacrimation

Question 25

functions of the parasympathetic system on the eye

Answer 25

- lets less light into the eye (constriction) - focuses eye on near objects - Reflex lacrimation (wash away foreign bodies) - allows orbularis oculi to work

Question 26

how do sympathetic fibres travel to the elevator palpebrae

Answer 26

- superior cervical sympathetic ganglion - internal carotid - internal carotid plexus - carried on ophthalmic artery - carried on branches of ophthalmic artery then opens eyes wider

Question 27

do sympathetic/parasympathetic fibres dilate the pupil

Answer 27

sympathetic

Question 28

what is a non-physiologically dilated pupil

Answer 28

mydriatic pupil caused by mydriatic drug

Question 29

in what direction are the DILATOR papillae fibres arranged

Answer 29

radially

Question 30

do parasympathetics/sympathetics constrict the pupil

Answer 30

parasympathetics

Question 31

what is a non-physiologically constricted pupil

Answer 31

mitotic pupil eg. component of horners syndrome

Question 32

what is the sensory part of the pupillary light reflex

Answer 32

CN II optic nerve

Question 33

what is the motor part of the pupillary light reflex

Answer 33

Oculomotor nerve CN III

Question 34

what happens when one eye is stimulated by light

Answer 34

direct light reflex occurs in the stimulated eye a consensual light reflex occurs in the non-stimulated eye

Question 35

what is the first neurone in the pupillary light reflex chain

Answer 35

retinal ganglion cells pass via optic nerve to optic chasm synapse in the pretectal nucleus in the midbrain

Question 36

what is the pathway of the second neurone in the pupillary light reflex chain

Answer 36

v small neurones in the midbrain which synapse in the Edinger Westphalia nucleus

Question 37

what is the path of the third neurone in the pupillary light reflex chain

Answer 37

from the Edinger Westphalia nucleus via CNIII to synapse at the ciliary ganglion

Question 38

what do the 4th neurones in the pupillary light reflex do

Answer 38

short ciliary nerves to the spinchter papillae muscles

Question 39

what ligament connects to the lens and the ciliary body

Answer 39

suspensory ligament

Question 40

what happens to the ciliary muscle when far vision is needed

Answer 40

it relaxes to flatten the lens to focus on objects in the distance

Question 41

what happens to the ciliary muscle when near vision is needed

Answer 41

it contracts so the suspensory ligaments relax and the lens becomes spherical

Question 42

what are basal tears

Answer 42

tears which clean/nourish and hydrate the avascular cornea contain lysosome to kill bacteria

Question 43

what are reflex tears

Answer 43

extra tears in response to mechanical stimuli or chemical stimulation sensed by ophthalmic nerve motor component - CNVII (facial)

Question 44

what are emotional tears

Answer 44

happy, sad or frightened tears

Question 45

what are the symptoms of horners syndrome

Answer 45

miosis (constriction) ptosis (drooping of upper eyelid) reduced sweating (anhydrosis) Increased warmth and redness

Question 46

what causes Horner's syndrome

Answer 46

impaired sympathetic innervation to the head and neck

Question 47

what are some causes of compression of the cervical parts of the sympathetic trunk

Answer 47

``` root of neck trauma carotid dissection internal jugular vein engorgement deep cervical node metastases pancoast tumour (lung apex) ```